GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc2602

Network Working Group M. Davison Request for Comments: 2602 Cisco Systems Category: Standards Track June 1999

                ILMI-Based Server Discovery for MARS

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

 This memo defines how ILMI-based Server Discovery, which provides a
 method for ATM-attached hosts and routers to dynamically determine
 the ATM addresses of servers, shall be used to locate MARS servers.

1. Introduction

 Presently, configuring a host or router to use MARS [1] is cumbersome
 and error-prone since it requires at least one ATM address to be
 statically configured on each host or router in the network.
 Further, it is impossible to implement a diskless host to use MARS
 since local configuration is required.  ILMI-based Server Discovery,
 hereafter referred to as "server discovery," provides a solution to
 these problems.
 A brief overview of the Integrated Local Management Interface (ILMI)
 and the Service Registry MIB, as defined by the ATM Forum, are
 provided in this memo. The reader should consult [2] for a complete
 description of ILMI and this MIB, but the information contained here
 is sufficient for an understanding of its use to support MARS server
 discovery.

Davison Standards Track [Page 1] RFC 2602 ILMI-Based Server Discovery for MARS June 1999

2. Integrated Local Management Interface

 The Integrated Local Management Interface (ILMI) [2] provides a
 mechanism for ATM-attached devices, such as hosts, routers, and ATM
 switches, to transfer management information. It is based on the
 Simple Network Management Protocol (SNMP), Version 1, and supports
 get, get-next, set and trap operations.
 The ILMI specification designates the switch side of the ATM link as
 the 'network side' and the host/router side of the ATM link as the '
 user side.' The Service Registry MIB, which is outlined in Section 3,
 is implmented on the network side and is queried from the user side.

3. ILMI 4.0 Service Registry MIB

 Server discovery utilizes the Service Registry MIB defined by the ATM
 Forum in ILMI Specification Version 4.0 [2]. To support the existing
 framework for IP over ATM, as embodied by ATMARP and MARS, ATM
 switches must support the Service Registry MIB.
 A row in the service registry table [2] is defined as:
            AtmfSrvcRegEntry ::= SEQUENCE {
                atmfSrvcRegPort          INTEGER,
                atmfSrvcRegServiceID     OBJECT IDENTIFIER,
                atmfSrvcRegATMAddress    AtmAddress,
                atmfSrvcRegAddressIndex  INTEGER,
                atmfSrvcRegParm1         OCTET STRING
            }

The definition of each field in this structure is:

    atmfSrvcRegPort - The ATM port number for which this entry
        contains management information. The value of zero may be used
        to indicate the ATM interface over which a management request
        was received.
    atmfSrvcRegServiceID - This is the service identifier that
        uniquely identifies the type of service at the address
        provided in the table. (See Section 3.2 for MARS OID.)
    atmfSrvcRegATMAddress - This is the full address of the service.
        The ATM client will use this address to establish a connection
        with the service.
    atmfSrvcRegAddressIndex - An arbitrary integer to differentiate
        multiple rows containing different ATM addresses for the same
        service on the same port.

Davison Standards Track [Page 2] RFC 2602 ILMI-Based Server Discovery for MARS June 1999

    atmfSrvcRegParm1 - An octet string whose size and meaning is
        determined by the value of atmfSrvcRegServiceID.
 The service registry table is indexed by atmfSrvcRegPort,
 atmfSrvcRegServiceID and atmfSrvcRegAddressIndex.

3.1 Service Parameter String

 A generic parameter string is defined in the service registry table,
 thus allowing protocol-specific parameters to be specified. To be
 consistent with [1], the parameter string for MARS shall be:
     mar$pro.type   16   bits     Protocol type
     mar$pro.snap   40   bits     Optional extension to protocol type
     mar$plen        8   bits     Length of protocol address
     mar$addr       plen octets   Network address
     mar$mask       plen octets   Network mask
 Where
     mar$pro.type   - See [1]. (IPv4 is 0x0800, IPv6 is 0x86DD)
     mar$pro.snap   - See [1]. (IPv4 and IPv6 are 0)
     mar$plen       - Length of the protocol address.
                      (IPv4 is 4, IPv6 is 16)
     mar$addr       - Network address represented in network byte
                      order
     mar$mask       - Network mask represented in network byte order

3.2 Service Object Identifier

 This OID, assigned in the ATM Forum Service Registry MIB, names MARS
 within the context of server discovery.
   atmfSrvcRegMARS   OBJECT IDENTIFIER ::= { 1.3.6.1.4.1.353.1.5.4 }
 It does not name any managed objects, rather is used to locate
 appropriate rows in the service registery table.

4. MARS Client Behavior

 A MARS client will access the service registry table via ILMI using
 the SNMP GetNext operator to "sweep" (SNMP parlance for a linear
 search) beginning with {Port = 0, ServiceID = <see Section 3.2>,
 Index = 0} while holding the port number and the serviceID constant.

Davison Standards Track [Page 3] RFC 2602 ILMI-Based Server Discovery for MARS June 1999

 (Port number 0 is used within ILMI to indicate "this port.")
 An MARS client with no local configuration, such as a diskless
 workstation, must use the row with the lowest index value if multiple
 MARS servers, possibly for multiple networks, are listed.
 MARS clients that have local IP configuration must use a row that has
 the appropriate IP address.  For example, consider the case where an
 IP router has 3 logical interfaces defined on a single physical
 interface with IP addresses 1.0.0.1/8, 128.10.0.1/16 and
 171.69.150.226/24. The router will sweep the service registry table
 looking for rows that have atmfSrvcRegParm1 values as shown below:
   Net number/mask  atmfSrvcRegParm1
   ---------------- --------------------------------------------------
   1.0.0.0/8        08 00 00 00 00 00 00  04  01 00 00 00  ff 00 00 00
   128.10.0.0/16    08 00 00 00 00 00 00  04  80 0a 00 00  ff ff 00 00
   171.69.150.0/24  08 00 00 00 00 00 00  04  ab 45 96 00  ff ff ff 00
 When the correct atmfSrvcRegParm1 values are located, the router may
 then establish an SVC to the selected server and perform the
 appropriate protocol operations.
 Redundant MARS servers are supported with multiple rows in the
 service registry table. This list of MARS servers is ordered with the
 primary MARS server having the lowest index value. The MARS client
 must attempt to utilize the primary MARS server before utilizing a
 secondary MARS server. Administrators must ensure that the listed
 MARS servers are synchronized.

5. MARS Server Behavior

 An MARS server shall be locally configured. The MARS server may
 retrieve the MARS service registry data to validate the results. If
 an incorrect row is retrieved the error may be flagged in a locally
 significant way.

Davison Standards Track [Page 4] RFC 2602 ILMI-Based Server Discovery for MARS June 1999

6. Relationship with PNNI Augmented Routing

 An augmented version PNNI ("PNNI Augmented Routing," or PAR) [3] has
 been developed by the ATM Forum. PAR can distribute data such as MARS
 server addresses. Further, the ATM Forum is developing a proxy
 mechanism for PAR (Proxy PAR) that would allow a UNI-attached host or
 router to access PAR data without a full PAR implementation.
 These mechanisms offer a promising way to manage the service registry
 tables maintained on each switch in an ATM network, yet would not
 require changes to the mechanism defined in this memo. Hosts and
 routers can continue to utilize ILMI-based or Proxy PAR-based server
 discovery and network administrators could manage the service
 registry data with local configuration or via PAR and Proxy PAR.

7. Security Considerations

 The server discovery mechanism is built on the ILMI managment
 framework and the security embodied in that framework. Access, to
 user- or network-side information is controlled by MIB design rather
 than protocol security mechanisms.
 The service registery MIB, the table containing information for
 server discovery, is defined in [2] with read-only access. This means
 that any user-side device may query the service registry, but may not
 modify the service registry via ILMI. Instead, the sevice registry
 table must be modified via local configuration on the ATM switch.

References

 [1]  Armitage, G., "Support for Multicast over UNI 3.0/3.1 based ATM
      Networks", RFC 2022, November 1996.
 [2]  ATM Forum, "Integrated Local Management Interface (ILMI)
      Specification Version 4.0," af-ilmi-0065.000, September 1996.
 [3]  ATM Forum, "PNNI Augmented Routing (PAR) Version 1.0," af-ra-
      0104, January 1999.

Author's Address

 Mike Davison
 Cisco Systems
 170 West Tasman Drive
 San Jose, California 95134
 Phone: (408) 526-4000
 EMail: mike.davison@cisco.com

Davison Standards Track [Page 5] RFC 2602 ILMI-Based Server Discovery for MARS June 1999

Full Copyright Statement

 Copyright (C) The Internet Society (1999).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Davison Standards Track [Page 6]

/data/webs/external/dokuwiki/data/pages/rfc/rfc2602.txt · Last modified: 1999/06/07 22:55 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki